Organ reed pickups with circuitry and lamp-photoresistor arrangement for percussive effects



y 26, 1970 c. E. MUSSULMAN 3,

ORGAN REED PICKUPS WITH CIRGUITRY AND LAMP-PHOTORESISTOR ARRANGEMENT FOR PERCUSSIVE EFFECTS Filed Nov. 6, 1967 2 Sheets-Sheet 1 Speaker Sgs Tem Amplifier y 6, 1970 c E. MUSSULMAN 3,514,522

ORGAN REED PICKUPS vim! CIRCUITRY AND LAMP-PHOTORESISTOR ARRANGEMENT FOR PERCUSSIVE EFFECTS iled Nov. 6. 1967 2 Sheets-Sheet 2 \Q &

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E R Q U INVENTOR Char/es E. Mussulman RNEYS.

United States Patent 3,514,522 ORGAN REED PICKUPS WITH CIRCUITRY AND LAMP-PHOTORESISTOR ARRANGEMENT FOR PERCUSSIVE EFFECTS Charles E. Mussulman, 1309 W. th, Chanute, Kans. 66720 Continuation-impart of application Ser. No. 525,200, Feb. 4, 1966. This application Nov. 6, 1967, Ser. No. 687,409

Int. Cl. Gb 3/00; G10h 1/02, 3/06 U.S. Cl. 84--1.18 Claims ABSTRACT OF THE DISCLOSURE In order to obtain a percussive or piano effect in an electric organ, a vibratory reed is associated with each tone key and is struck when the key is depressed, and thereafter damped when the key is released. A transducer (e.g., electromagentic or photoelectric) converts the mechanical vibration, which will have a decaying amplitude characteristic, into an electrical control signal that imparts its amplitude characteristic to an audio signal delivered by the appropriate tone source to the amplifier and speaker system of the organ. A pair of transistors and a pair of lamps with light dependent resistors are provided between the transducer and the output.

This application is a continuation-in-part of my copending application Ser. No. 525,200, filed Feb. 4, 1966, and entitled Decay Converter for Electric Piano or Oragn, now abandoned.

This invention relates to apparatus for producing percussive elfects in electric musical instruments and, more particularly, to apparatus which may be utilized in conjunction with an electric organ to convert the same into an electric piano.

Although electric organs have become quite popular 'in recent years, a number of problems have confronted workers in this field when it is attempted to design an electric piano suitable to the practicing musician. Unlike an organ, a piano must be sensitive to the touch of the player and, additionally, the musical tones produced must have a particular amplitude decay characteristic in order to create a piano-like tonal effect.

It is, therefore, the primary object of this invention to provide apparatus for producing musical tones in response to the operation of a piano or organ keyboard, wherein such tones have initial amplitudes which are controlled by the striking force applied to the keys to thereby render the tone amplitudes sensitive to the touch of the player.

As a corollary to the foregoing object, it is an important aim of this invention to provide apparatus as aforesaid capable of imparting an amplitude decay characteristic to the tones produced in a manner to create a percussive effect recognizable as the sound of a piano.

Another important object is to provide such apparatus with means for substantially increasing the damping rate of the tones produced upon release of the associated tone keys by the player, thereby further enhancing the percussive effect characteristic of a piano instrument.

Still another important object is to provide apparatus as aforesaid which utilizes an electrically responsive, variable impedance switching arrangement interposed between the output of a tone source and subsequent amplifier stages and speakers of the sound system of an electric piano or organ, the switching arrangement being operable in response to a control signal derived independently of the audio signal from the tone source output and produced in response to player actuation of a corresponding tone key.

Yet another aim is to provide a means of imparting an amplitude decay characteristic to the control signal which essentially duplicates the natural damping of a note produced by a conventional piano, and to achieve this effect through the use of a vibratory member which is struck in response to actuation of a tone key and a transducer which converts such vibrations into the aforesaid control signal.

A further and important object is to provide such a transducer in which conversion of the mechanical vibration of the member into the electrical control signal is accomplished through the use of the member as a means of controlling the impinging of light radiation upon a photosensitive element.

An additional object is to provide a key-click free, player actuated tone switching arrangement for an electric organ which couples a selected tone source to the following amplifier stages and speaker system of the organ in response to actuation of the key, through the use of a pair of photoresistive elements controlled and arranged in a manner to prevent leakage of the audio tone signal therethrough to the subsequent amplifier stages regardless of capacitive coupling effects.

In the drawing:

FIG. 1 is a diagrammatic and schematic illustration of one form of the invention;

FIG. 2 is a diagrammatic and schematic illustration of a second form of the invention; and

FIG. 3 is a diagrammatic illustration of a multi-key transducer of the type shown in FIG. 2.

The numeral 10 designates a tone source which may comprise an audio oscillator capable of continuously delivering an output signal at constant amplitude. The output signal from tone source 10 would have a frequency equal to one of the tones of the musical scale; therefore, a tone source 10a is also illustrated for providing another note of the musical scale. It will be appreciated that the number of tone sources utilized depends upon the keyboard range of the instrument. Additionally, it should be understood that the signals produced by the tone sources may be derived from recording of an actual organ, piano or other instrument which it is desired to electrically duplicate by the apparatus of the instant invention.

Tone source 10 is provided with a pair of output connections as illustrated by leads 12 and 14, the latter being connected to a common ground as indicated. Lead 12 is connected to a photoresistive element 16 which may comprise a cadmium selenide, lead sulfide, or cadmium sulfide photocell. A similar photoresistive element 18 is connected in series with element 16 between the latter and ground connection 20. A terminal 22 between the series connected elements 16 and 18 serves as a connection point for the input of an audio amplifier 24 which, in turn, drives a speaker system 26. Amplifier 24 and speaker system 26 are units common to the various tone sources of the instrument and, in the FIG. 1, represent conventional subassemblies of an electric organ.

It should be understood at this juncture that lamps 28 and 30 are employed in conjunction with circuitry to be described hereinafter to control the impedances of elements 16 and 18 by the intensity of the light emanating from lamps 28 and 30. Normally, when it is not desired that the audio signal or note from source 10 be permitted to flow to amplifier 24, element 16 is maintained at a high impedance and element 18 at a low impedance, thereby effectively blocking the passage of the signal to terminal 22 and shorting any portion of the signal that leaks across Patented May 26, 1970 element 16 to the ground connection 20. These states of the elements 16 and 18 are reversed in response to actuation of the tone key corresponding to the note produced by source therefore, speaker system 26 then delivers the tonal sound. The circuitry which controls the energization of lamps 28 and 30 may be operated in a manner to impart a percussive effect to the sound produced by speaker system 26 or, alternatively, may be operated in a manner to produce an organ efiect, depending on the mode of operation desired by the player. By way of definition, a percussive effect is descriptive of the sound produced by a percussion instrument, such as a piano, where the sound produced has a decaying amplitude characteristic; an organ effect as discussed herein refers to the production of a sound of constant amplitude which ceases immediately upon release of the tone key.

The tone key corresponding to tone source 10 is illustrated diagrammatically at 32 and swings in a clockwise direction through a small displacement about a pivot 34 when the key is depressed or struck by the player. A vibratory member 36 in the form of a magnetic reed is cantilever supported by a clamping block 38 and is normally restrained against vibration by a damper 40 coupled to key 32 by a suitable support 42. A hammer 44 is pivoted on a pin 46 and is provided with a head 48 engageable with reed 36 when the hammer is actuated. A return spring 50 holds hammer 44 in the normal position shown.

A hammer actuator '52 pivots on a pin 54 and is provided with a pawl at its upper end which hooks over the adjacent end of hammer 44 when the latter is in its normal position. Pawl 56 is pivoted at its lower end on a pin 58 carried by the upper end of actuator 52, and biased in a counterclockwise direction by a spring 60 against a retainer 62. A return spring for the actuator is illustrated at 64 and normally holds the lower end thereof in engagement with the adjacent end of key 32.

A transducer in the form of a magnetic pickup 66 is disposed adjacent reed 36 and may comprise a coil of wire having a permanent magnet core, as illustrated. Connections to the ends of the coil are made via leads 68 and 70 which are connected to the input of an AC amplifier stage 72. The tip of reed 36 is disposed in the magnetic field produced by pickup 66 so that vibrations of the reed will be detected by the pickup and converted into a control signal which is fed to the input of amplifier 72.

The output of amplifier 72 is coupled to the base of a PNP transistor 74 by a coupling capacitor 76, transistor 74 being operated as a direct current amplifier. Collector voltage for transistor 74 is supplied by a suitable direct current source (not shown) coupled between a power supply terminal labeled V and ground. The -V terminal is connected to the collector of transistor 74 via variable resistor 78, lead 80, and resistor 82.

A diode 84 is connected between the base of transistor 74 and ground and serves as a rectifier or clipper which permits only the negative half cycles of the output of amplifier 72 to be conducted to the transistor base. A filter condenser 86 is connected between the emitter of transistor 74 and ground.

A second transistor 88 is operated as a variable impedance switching device, the base of transistor 88 being directly connected to the emitter of transistor 74, while the emitter of transistor 88 is connected to ground. The collector of transistor 88 is connected to lead '80 via lamp 28 and a resistor 90 connected in parallel with lamp 28. Lamp 30 is connected in series with lamp 28 and to ground by a lead 92. Lamps 28 and 30 are disposed to direct illumination against elements 16 and 1'8, respectively, as indicated by the arrows.

A lead 94 extends from terminal 22 to the other noteproducing apparatuses of the organ. Each of these is identical to the structure and circuitry just described hereinabove, except that the various tone sources will, of course, deliver audio signals of different frequencies. The control signal source 96 and amplitude control circuitry 4 98 associated with tone source 10a control the delivery of the output of the source to a terminal 22:: to which lead 94 is connected. Thus, the input of amplifier 24 is common to all of the various key-controlled tone sources which deliver output signals thereto in accordance with the musical composition being played.

In this regard, it may be desired to mix various of the tone sources in order to provide notes having harmonic compositions which are the same as the notes actually produced by a piano. The notes of the lower registers of the piano are mixtures of the fundamental and higher harmonics. Thus, the frequency content of a true piano note may be duplicated by paralleling the proper tone sources, with attention being given to the values of suitable impedances in series with the harmonic sources to reduce their amplitudes relative to the fundamental to provide the proper amplitude blend for a given note.

Lead 12 is connected to lead 70 and one side of the input of amplifier 72 by a lead 100 having a pair of switches 102 and 104 connected in series therein. Switch 104 is normally open and is closed by the actuation of key 32 through a suitable mechanical linkage illustrated diagrammatically at 106. Switch 102 serves as a selector switch and, when open as shown, permits the apparatus to operate in a manner to produce percussive effects. When closed, the apparatus operates to produce a conventional organ effect. It should be understood that, in practice, the switch 102 of each of the note-producing apparatuses would comprise one pole of a ganged, rnulti-pole switch or, alternatively, a relay, in order that all of the switches 102 may be controlled in unison by a single selector operated by the player.

In operation, with switch 102 open, actuation of key 22 pivots actuator 52 in the direction indicated by the arrow to, in turn, impart striking force to the head 48 of hammer 44. Movement of the hammer is initiated by pawl 56 which shifts downwardly as actuator 52 pivots. Spring 50 immediately returns hammer 44 to the normal position shown after it strikes reed 36, whereupon pawl 56 returns to the position illustrated when key 32 is released.

Additionally, as key 32 is depressed, damper 40 moves away from reed 36 so that, when struck by the hammerhead 48, the reed vibrates freely under the effect of natural clamping only. The vibration of the reed is converted into an oscillatory control signal by transducer 66 which, in turn, is applied to the input of amplifier 72.

The reed vibration is at maximum amplitude at the time the reed is struck. Without external damping, the amplitude of the vibration will slowly decay to, zero. The harder the reed is struck, the greater the initial amplitude and the longer the decay period. Both the amplitude and the decay characteristic can be controlled by the size, length, and material of the reed. The physical properties of the reed may be selected such that its vibrational characteristics are similar to the characteristics of a vibrating string.

Since strings are utilized in pianos as the sound sources thereof, it is evident that a properly selected reed will, insofar as its decay characteristic is concerned, produce the same effect as the vibration of a piano string. The decay characteristics of large piano strings (the lower notes of the keyboard) are much different than the decay characteristics of the string of higher clefs; thus, the properties of each reed are selected in accordance with the decay characteristic of the particular tone with which it is associated.

Although transducer 66 is illustrated as a magnetic pickup, it should be understood that a suitable ceramic, crystal, or capacitive type of pickup could be substituted. The function of transducer 66 is to acurately convert the vibratory motion of the reed into an oscillating control signal capable of amplification by amplifier 72 to a suitable level. The frequency of the control signal, however, is unimportant since this signal is only utilized to control the output from tone source 10. Therefore,

reed 36 may be selected to produce the desired amplitude envelope without regard to the frequency of vibration. Resistor 78 is set such that, with reed 36 fully damped, lamp 28 is off. Under such conditions, the output from transistor 74 is at a low level and the emitter-collector circuit of transistor 88 is nonconductive. Lamps 28 and 30 may comprise low voltage bulbs such as commonly utilized with flashlight cells, lamp 28 being selected such that its internal resistance is on the order of one-half of the resistance of lamp 20. This, in conjunction with resistor 90 which may be chosen to have a value substantially equal to or less than the resistance of lamp 28, results in the establishment of a considerably higher voltage drop across lamp 30 than across lamp 28 when transistor 88 is nonconductive. Thus, only lamp 30 is supplied with sufiicient voltage to emit light under this condition. This maintains element 16 in a high impedance state and element 18 in a relatively low impedance state to positively preclude the delivery of the output signal from source to terminal 22.

The internal capacitance of photocells in the high impedance state may permit an audio frequency signal to leak therethrough even though the resistance of the cell may be quite high. For this reason, the provision of the shunt element 18 assures that, if any such leakage should occur through element 16, the signal will be shunted to ground through the excited element or cell 18.

Actuation of key 32 and production of a control signal by transducer 66 causes transistor 74 to produce a DC output signal having an amplitude which decays in accordance with the decaying amplitude envelope of the control signal. This initially gates the emitter-collector circuit of transistor 88 into conduction to a degree dependent upon the amplitude of the gating signal from amplifier 74 and effectively establishes a low impedance connection across lamp 30. Thus, lamp 28 will light and the states of the two elements 16 and 18 Will reverse.

As the control signal decays, the impedance of the emitter-collector circuit of transistor 88 gradually rises in accordance with the decreasing output signal delivered by transistor 74. Thus, lamp 30 is returned to a lightemitting condition and gradually increases in brilliance as the control signal decays. This, in turn, is accompanied by a gradual decreasing in the brilliance of lamp 28. The cumulative efiect of this acton is to gradually increase the impedance to the flow of the output signal from source 10 to terminal 22, thereby progressively diminishing the amplitude of the sound heard by a listener.

If at any time during the decay of the control signal the player releases key 32, damper 40 immediately effects complete damping of reed 36 and the sound ceases substantially instantaneously. This is in accordance with piano action, it being evident that damper 40 and hammerhead 48 control the vibrating reed 36 much in the same manner as the hammers and dampers of a piano control the vibration of respective note strings. Additionally, hammer actuation is effected in a manner analogous to a piano action so that the striking force applied to the hammer will be proportional to the striking force applied to the key by the player. Therefore, the apparatus is sensitive to the touch of the player and the initial amplitude of the sound is dependent upon the force with which the key is struck.

When a conventional organ effect is desired, closure of switch 102 delivers a portion of the audio signal from source 10 to the input of amplifier 72 when key 32 is actuated. Thus, regardless of the vibration of reed 36, transistor 88 is placed in conduction and remains in the conductive state without viriation until the key is released. The amplitude of the signal from tone source 10 delivered to amplifier 72 is of substantially greater magnitude than the control signal produced by transducer 66; therefore, transistor 88 is placed in hard conduction and is not affected by the control signal incidentally produced by transducer 66.

Referring to FIG. 2, the second form of the instant invention there shown is operationally similar to the embodiment of FIG. 1, like structure being designated by the same reference characters utilized in FIG. 1 with the addition of the prime notation. A pair of PNP transistors 200 and 202 comprise the amplitude control circuitry, with the control signal being produced by a.

transducer comprising a light source 204 and a photoresistive element 206.

The vibratory member 36' has its free end portion 208 bent at right angles to the main body of the member, such end portion 208 being normally disposed between the light source 204 and element 206. In this embodiment of the invention, member 36 need not be of magnetic material since the transducer arrangement to be discussed in detail hereinafter does not rely upon magnetic properties for its operation.

The source 204 may comprise a low voltage bulb of the same type as lamps 28 and 30 or 28' and 30', and element 206 is a light dependent resistor of the type discussed above with respect to elements 16 and 18. The end portion 208 of member 36' normally blocks the passage of light rays from source 204 to element 206, the latter thus being normally in a high resistance condition. The element 206 is in the input circuit of transistor 200 between the base and collector thereof, such collector being connected to the negative DC supply terminal designated -V. The emitter of transistor 200 is directly connected to the base of transistor 202, the latter having its collector connected to the common interconnection of lamps 28 and 30' and resistor The emitter of transistor 202 is grounded as indicated by the symbol to place the emitter-collector circuit of transistor 202 in parallel with lamp 30'.

In operation, both of the transistors 200 and 202 are normally nonconductive due to the high ohmic value of the resistive element 206. The vibratory member 36 is disposed to vibrate in directions generally normal to the plane of the drawing of FIG. 2 so that the end portion 208 will move out from between source 204 and element 206 during vibration of member 36. Such vibra t1on is initiated in the same manner as illustrated in FIG. 1 and discussed hereinabove through the actuation of a hammer 44 by the depressing of tone key 32.

-It may be appreciated that source 204, member 36 and element 206 could be positionally interarranged in a number of ways to achieve the desired effect of exposing element 206 to repeated bursts of light radiation as member 36' vibrates. The bent end portion 208 is illustrated herein as being a preferred arrangement in the interest of conserving space.

Since the displacement of vibratory member 36' away from its normal or at-rest position is maximum at the commencement of vibration and progressively decreases as discussed hereinabove, the intensity of each light burst lmpinging upon element 206 will decrease with time. This occurs because, each time member 36 moves away from its at-rest position, it nnblocks a lesser portion of the light radiation produced by the source 204. It may be desired to position end portion 208 such that it effectively uncovers source 204 only during movement in one direction away from the normal position, corresponding to each half cycle of vibration.

From the foregoing, it is clear that the mechanical oscillation of member 36 is reproduced in the varying resistive characteristic of element 206, with the result that the emitter-collector circuit of transistor 200 is placed in conduction each time a light burst arrives at element 206. This, in turn, renders the emitter-collector circuit of transistor 202 conductive to a degree dependent upon the resistance of element 206. When member 36 is initially struck and the amplitude of the vibration is greatest, lamp 30', which is normally on, is reduced significantly in brilliance or completely shorted across with attendant energization of lamp 28'. The resistor 90' is selected of a value to maintain lamp 28' bit in the absence of a control signal as discussed above with respect to the embodiment of FIG. 1. Furthermore, in the FIG. 2 arrangement, resistor 90 is selected to provide the lamp 28 with a maximum brightness approximately one-half of the maximum brilliance of the other lamp 30'. Under this condition, considering the two parallel resistive arms formed by element 18 and the combination of element 16' and tone source the added series resistance of tone source 10 is compensated for to an extent to cancel the periodic component of the control signal which would otherwise be impressed upon the audio signal delivered by tone source 10 across its output connections 12 and 14. This is requisite in order to prevent modulation of the audio signal from tone source 10 by the periodic com ponent of the control signal. As in the first embodiment of the invention illustrated in FIG. 1, it is desired that the audio signal from tone source 10" decay in amplitude in accordance with the amplitude envelope of the control signal without regard to the frequency of vibration of member 36'.

A lead 210 extends from the V supply terminal to the base of transistor 200, switches 102 and 104 being interposed in series therein. Thus, if an organ etfect is desired rather than a percussive elfect, switch 102' is closed so that the closure of switch 104' by actuation of the tone key will place transistor 200 in hard and steady conduction.

Refering to FIG. 3, a multi-key transducer is illustrated for use with a bank of tone keys arranged in the usual keyboard fashion. The light source is in the form of a fluorescent bulb 212 but may comprise a series of incandescent lamps if desired. The bulb .212 is disposed within an enclosure illustrated fragmentarily, such enclosure having a wall 214 provided with a series of spaced apertures 2.16 therein. Each of four of the apertures is illustrated in alignment with a corresponding photoresistive element 206a, 206b, 206a or 206d. The light blocking end portions 208a, 208b, 2086 and 208d of corresponding vibratory members normally prevent light rays passing through apertures 216 from impinging upon elements 206a-206d. In this manner, a simple and compact structural arrangement is provided which is particularly suitable for use with the tone keys of an organ since the keys are closely spaced and require that the hammers and associated mechanical components be confined in limited space.

It may be appreciated that the embodiment of FIG. 2 has certain advantages over and above the form of the invention illustrated in FIG. 1. The embodiment of FIG. 2 is less expensive and quite compact, and also has a faster response time in that no capacitive reactance is present .in the circuitry. The initial excursion of the Wave form of the control signal is steeper to more nearly duplicate the percussive efiect of a hammer striking a piano string. Freedom from control signal modulation in the tone source output is assured due to phase cancellation in the two photoresistive elements 16' and 18.

Having thus described the invention, what is claimed as new and desired to be secured by Letters Patent is:

1. In an electric percussion instrument: a tone source for providing an audio signal; means for coupling said source with apparatus for converting said audio signal into sound; player-actuated means for producing a control signal having a decaying amplitude characteristic corresponding to a desired percussive effect; and amplitude control means coupled with said source and said player-actuated means and responsive to said control signal for varying the amplitude of the audio signal delivered to said coupling means by said source in accordance with said characteristic, said player-actuated means including an actuable tone key, a vibratory member, means responsive to actuation of said key for striking said member to initiate vibration thereof, and transducer means operably associated with said member for converting said vibration into said control signal.

2. The invention of claim 1,

said key having a normal, released position,

said player-actuated means further including a movable damper coupled with said key and contacting said member when the key is in said normal position,

said key being operable to move said damper away from said member upon actuation of said key, whereby to permit undamped vibration of the member until the key is released, thereby imparting a piano elfect to said audio signal.

3. The invention of claim 1,

said control means including circuitry for providing said delivered audio signal With an initial amplitude governed by the initial amplitude of said control signal,

said striking means including a movable hammer engageable with said member and structure for imparting striking force to said hammer of a magnitude dependent upon the actuating force applied to said key, whereby the amplitude of the delivered audio signal is sensitive to the touch of the player to thereby create a piano effect.

4. The invention of claim 3,

said key having a normal, released position,

said player-actuated means further including a movable damper coupled with said key and contacting said member when the key is in said normal position,

said key being operable to move said damper away from said member upon actuation of said key, whereby to permit undamped vibration of the member until the key is released, thereby further enhancing the piano effect.

5. The invention of claim 1, said member comprising a cantilever supported reed.

6. The invention of claim 1,

said control means including circuitry for providing said delivered audio signal with an initial amplitude governed by the initial amplitude of said control signal,

said striking means being responsive to actuation of said key for providing said control signal with an initial amplitude dependent upon the actuating force applied to said key, whereby to render the amplitude of the delivered audio signal sensitive to the touch of the player.

7. The invention of claim 1,

said source having an output for presenting said audio signal provided thereby,

said control means including variable impedance means operably interposed between said output and said coupling means, and circuitry for varying the impedance presented to said audio signal by said variable impedance means in accordance with the amplitude of said control signal,

said striking means being responsive to actuation of said key for providing said control signal with an initial amplitude dependent upon the actuating force applied to said key, whereby to render the amplitude of the delivered audio signal sensitive to the touch of the player.

8. In an electric precussion instrument:

a tone source for providing an audio signal at its outmeans for coupling said output with apparatus for converting said audio signal into sound;

player-actuated means provided with an actuatable tone key and operable to produce a control signal having an attack and a decaying amplitude characteristic corresponding to a desired percussive effect and an initial amplitude dependent upon the actuating force applied to said key; and

amplitude control means coupled with said player-actuated means and operably interposed between said output of the source and said coupling means for receiving said audio signal,

said control means being responsive to said control signal for varying the ampltiude of the audio signal delivered to said coupling means in accordance with said characteristic, and including a first variable impedance element coupled in series between said output and said coupling means to provide an audio signal circuit from said output to said coupling means, a second variable impedance element coupled in shunt relationship to said circuit, and operating circuitry associated with said elements and normally maintaining said first and second elements at relatively high and low impedance values respectively,

said operating circuitry being operable in response to said control signal to respectively lower and raise the impedance values of said first and second elements by amounts governed by the amplitude of said control signal.

9. The invention of claim 8, said player-actuated means including an actuatable tone key, a vibratory member, means responsive to actuation of said key for striking said member to initiate vibration thereof, and transducer means operably associated with said member for converting said vibration into said control signal.

10. The invention of claim 9,

said control means having an input coupled with said player-actuated means for receiving said control signal,

there being selectively operable means for exciting said operating circuitry in a manner to cause lowering and raising of the impedance values of said first and second elements respectively to constant levels,

said player-actuated means being provided with a normally open switch coupling said selectively operable means with said input,

said key being operable to close said switch upon actuation thereof whereby, upon operation of the selectively operable means, closure of said switch by the key provides an organ effect rather than said percussive effect.

11. The invention of claim 8,

said elements being photoresistive,

said operating circuitry including first and second lamps for exciting said first and second elements, respectively, and means normally maintaining said second lamp in light emitting condition and operable to excite said first lamp and simultaneously reduce the excitation to said second lamp in response to the initial amplitude of said control signal, and thereafter progressively return the lamps to the normal conditions thereof as the amplitude of the control signal decays.

12. In an electric organ:

a tone source for providing an audio signal across a pair of output connections thereof;

a terminal for coupling said source with apparatus for converting said signal into sound;

a first photoresistive element coupled in series between one of said connections and said terminal to provide an audio signal circuit from said one connection to said terminal;

a second photoresistive element coupled in shunt rela-. tionship between said circuit and the other of said connections;

first and second lamps for exciting said first and second elements respectively;

operating means coupled with said lamps and normally maintaining said second lamp in light-emitting condition to thereby establish a conduction path for said signal across said connections; and

a player-actuatable tone key coupled with said operating means,

the latter being operable in response to actuation of said key to excite said first lamp and simultaneously reduce the excitation to said second lamp, whereby the signal is available at said terminal when the key is actuated.

13. The invention of claim 12,

said operating means including electrically responsive switching means having a control input; and

circuit means connecting said one connection with said input and including a normally open switch coupled with said key and operable to establish electrical continuity between said one connection and said input upon said actuation of the key.

14. The invention of claim 13,

said operating means further including an energizing circuit connecting said lamps in series and in a manner to normally provide a substantially lesser voltage drop across said first lamp than across said second lamp,

said switching means including a direct current amplification stage, rectifier means operably coupling said input with said stage, and an active electrical device coupled with said second lamp and responsive to the output of said amplifier stage for establishing a short circuit across said second lamp.

15. The invention of claim 12,

said operating means including electrically responsive switching means having a control input; and

circuit means connected to said input for coupling the latter with a supply of direct current electrical energy, and including a normally open switch coupled with said key and operable to establish electrical continuity between said supply and said input upon said actuation of the key.

16. In combination with an electric percussion instrument having a tone source for providing an audio signal and amplitude control means for varying the amplitude of said audio signal in accordance with the amplitude of a control signal, player-actuated apparatus for producing said control signal with an amplitude decay corresponding to a desired percussive effect, said apparatus comprising:

a light responsive electrical element having an electrical characteristic which is dependent upon light radiation impinging on said element;

a light source for exciting said element;

a vibratory member having a normal, at-rest position blocking travel of light rays from said source to said element;

an actuable tone key; and

means responsive to actuation of said key for striking said member to initiate vibration thereof and cause the member to shift out of light-blocking relationship to said element, whereby said electrical characteristic of the element varies as the member moves away from and returns to said normal position during each vibration thereof to thereby produce said control signal.

17. The invention of claim 16,

said element being photoresistive,

there being circuit means coupled with said element and cooperating therewith to produce said control signal in response to variation of the resistance of said element.

18. The invention of claim 16,

there being a plurality of said elements; and

structure for directing the light rays from said source to each of said elements along independent paths,

there being a plurality of said members each normally disposed in a corresponding path, and a plurality of said tone keys and said striking means for initiating vibration of individual members.

19. In an electric percussion instrument:

a tone source for providing an audio signal at its outmeans for coupling said output with apparatus for converting said audio signal into sound;

player-actuated means provided with an actuatable tone key and operable to produce a control signal having an attack and a decaying amplitude characteristic corresponding to desired percussive effect and an initial amplitude dependent upon the actuating force applied to said key; and

amplitude control means coupled with said playeractuated means and operably interposed between said output of the source and said coupling means for receiving said audio signal,

said control means being responsive to said control signal for varying the amplitude of the audio signal delivered to said coupling means in accordance with said characteristic,

said player-actuated means including a vibratory member, means responsive to actuation of said key for striking said member to initiate vibration thereof, and transducer means operably associated With said member for converting said vibration into said control signal.

References Cited UNITED STATES PATENTS Miessner 841.13 X Mendelson 250201 Oliwa 340-345 Markowitz 841.1 Welsh 84-118 Slaats et al. 841.27 X Barber 84-1.27 X Meinema .e 841.26 X

WARREN E. RAY, Primary Examiner US. Cl. X.R. 

